Many types of fiber optics switches are in the market now. A number of patents are exemplary of the type of optical switches currently commercially available; see, e.g., U.S. Pat. No. 4,378,144, entitled "Optical Switch" and issued on Mar. 29, 1983, to G. S. Duck et al; U.S. Pat. No. 4,896,935, entitled "Fiber Optic Switch" and issued on Jan. 30, 1990, to H.-S. Lee; U.S. Pat. No. 5,005,934, entitled "Fiber Optics Channel Selection Device" and issued on Apr. 9, 1991, to L. E. Curtiss; and U.S. Pat. No. 5,420,946, entitled "Multiple Channel Optical Coupling Switch" and issued on May 30, 1995, to J.-H. Tsai. To make a compact design, the fibers may be arranged differently, see, e.g., U.S. Pat. No. 5,629,993, entitled "Compact Optical Switch" and issued on May 13, 1997, to J. O. Smiley.
All of the foregoing designs depend on difficult-to-attain precise mechanical alignment. For example, in U.S. Pat. Nos. 4,378,144, 4,896,935, 5,420,953, and 5,629,993, the alignment is between moving and stationary parts, while in U.S. Pat. No. 5,005,934, the alignment is between stationary parts which are far away from each other.
U.S. Pat. No. 5,173,958, entitled "Beam Distributor for Laser-to-Optical Fiber Application" and issued on Dec. 22, 1992, to M. F. Folsom et al, discloses an eccentrically mounted retroreflector prism in a cylindrical housing having a plurality of lenses and associated optical fibers distributed about the central axis of the housing. The prism is driven to revolve about the central axis and, as it does so, to sequentially direct a beam which is incident along the central axis to respective lenses and optical fibers in turn, by retroreflection. A drawback with this arrangement is the use of a prism retroreflector comprising a bulk prism. Such a bulk prism adds weight to the system and its front face introduces unwanted light reflection.
U.S. Pat. No. 5,481,631, entitled "Optical Switching Apparatus with Retroreflector" and issued on Jan. 2, 1996, to J. E. Cahill et al, discloses use of a retroreflector, or corner cube reflector, mounted on a stepper motor to be selectively positioned so as to direct light from one optical fiber to another. However, the reference does not describe how the retroreflector is constructed.
Thus, what is needed is a fiber optics switch where all alignments are between parts that are in relatively close proximity to each other and do not have relative motion. Ideally, a compact design is desired, to reduce space requirements. Also ideally, the optical fibers should be stationary. Finally, the retroreflector must be reconfigured to reduce weight and increase switching speed.